Conventionally, techniques for inkjet recording have been and are being developed in the technical field pertinent to commercial printing. In the inkjet recording, ink droplets are discharged onto a recording medium and subjected to an energy for subsequent treatment so as to fix an image on the recording medium. For example, a known apparatus has a rectangular head holder that holds a plurality of recording heads through which droplets of ultraviolet-curable inks can be discharged, and a pair of ultraviolet light source units disposed at both ends of the head holder (Patent Literature 1).
The generally called multi-pass (or shuttle pass) recording scheme includes “bidirectional recording mode” that allows printing to be performed at high speeds. In this recording mode, an image is formed with ink droplets discharged from a recording head at timings of forward and backward scans being performed. This recording mode, however, may generate variability in image quality (non-uniform image quality) between parts of an image respectively formed in the forward and backward scans.
Patent Literature 2 describes an apparatus equipped with a plurality of recording heads, and filters that transmit therethrough ultraviolet light of a certain wavelength. The recording heads are arranged in stepwise formation, and the filters are arranged likewise correspondingly to the recording heads. It is further described in this patent literature that the ink droplets that have landed on the recording medium in forward and backward scans can be irradiated with ultraviolet light at equal timings, which advantageously suppresses variability in image quality.